$ perl -e 'sub {die}'
[download]

is just setting up an anonymous subroutine in void context then exiting with a normal termination status because it never actually dies. Note the following

$ perl -e '$sub = sub {die}; $sub->();'
Died at -e line 1.
$ echo $?
255
$
[download]

Cheers,

JohnGG

Update: To test behaviour in a script rather than on the command line.

use strict;
use warnings;

sub toDieFor
{
    my $v = shift;
    die qq{Died with $v};
}

my $value = shift;
toDieFor($value) if $value > 10;
print qq{Normal termination\n};
[download]

Running this a couple of times

$ spw638035 3
Normal termination
$ spw638035 33
Died with 33 at spw638035 line 9.
$ echo $?
255
$
[download]

Perhaps you could shows us an actual code sample that triggers the behaviour you describe.